In the previously known devices for measuring the position of motor vehicle wheels, as are known from e.g. DE 10 2010 039 246 A1 and DE 10 2009 029 241 A1, measurement objects provided with measurement marks, so-called targets, are fastened to the wheels of the vehicle with the aid of special adapters. The targets attached to the wheels are artificially illuminated by an illumination device by way of light flashes or continuous light and images of the targets are recorded by cameras (usually 3D stereo cameras). The positions of the targets, and hence also the positions of the wheels, in space are established using special image processing algorithms, such as e.g. contour analysis, ellipse fitting or centroid determination for the marks on the targets (see e.g. DE 10 2008 042 024 A1). The influences of changing ambient light are largely eliminated by the artificial illumination of the targets during the measurement.
The artificial illumination of the objects to be measured leads to higher manufacturing costs of the measuring installation due to an additional hardware-technological outlay in terms of light-emitting diodes, lasers, lamps and/or projectors.
In order to improve the used/interference light ratio between the artificial illumination and the ambient light, the marks on the targets are often made from a reflecting film or from reflecting dye (retroreflective marks), which has as a consequence higher manufacturing costs in relation to a target printed with a normal dye.
It is therefore an object of the disclosure to provide a cost-effective device and a cost-effective method for measuring vehicles, in which, in particular, it is possible to dispense with artificial illumination and retroreflective marks.